The present invention is generally directed to inks, and more specifically to thermal ink jet inks and processes thereof. In embodiments, the present invention is directed to inks containing a dissipatible polymer and a zwitterionic additive, such as betaine, and which inks possess a number of advantages, such as reduced or minimal smear without for example, heating, increased paper latitude, reduced cool, or room temperature paper curl, and the like. The inks of the present invention in embodiments also possess excellent waterfastness, superior smear resistance, and high optical densities of for example from about 1.4 to about 1.6 as measured using a MacBeth or X-Rit densitometer compared to some other inks without betaine wherein the optical density thereof is from about 1.2 to about 1.3. The present invention in embodiments thereof enables the utilization of polymers obtained by polycondensation reactions, such as polyesters, and more specifically, the sulfonated polyesters as illustrated in U.S. Pat. No. 5,348,832, and U.S. Pat. No. 5,604,076, the disclosures of which are totally incorporated herein by reference. Sulfopolyester resins which can be selected for the invention inks, are known and are generally available commercially from Eastek Inks, a business unit of Eastman Chemical Company. These sulfopolyester resins are suitable for use in overprint lacquers and primers, as described in Kenneth R. Barton, "Sulfopolyesters: New Resins for Water-Based Inks, Overprint Lacquers and Primers", American Ink Maker, pp. 70-72 (October, 1993).
Thermal ink jet printing processes, and which processes may be selected for the inks of the present invention, are described in more detail, for example, in U.S. Pat. Nos. 5,169,437 and 5,207,824, the disclosures of which are totally incorporated herein by reference.